South Korea and Japan are working to prevent a diplomatic confrontation over disputed islands from escalating. Authorities in Seoul say they hope diplomacy will be successful, but warn that Japan will be to blame if events at sea take a turn for the worse.

South Korean Foreign Ministry spokesman Choo Kyu-ho said a "physical clash" remained a possibility Thursday, as Japanese and South Korean vessels prepare for a potential face-off in disputed waters.

Japan says it is briefly delaying plans to conduct an oceanographic survey near islands claimed by both nations. South Korea calls the islands Dokdo. Japan, which calls them Takeshima, seized the islands in 1905, when it imposed 35 years of harsh colonial rule on the Korean peninsula.

South Korean authorities at the highest levels are denouncing Tokyo's survey plans as an aggressive provocation. Officials here on Thursday rejected Japan's offer to call off the survey, if South Korea would abandon attempts to give Korean names to maritime features in the area.

At least 20 South Korean coast guard vessels backed by aircraft are heading to the disputed area. Japanese media report two Japanese coast guard vessels are preparing to conduct the controversial survey. Forecasters have predicted high winds and waves in the area, but Tokyo says an attempt at diplomacy, and not the weather, has delayed the mission temporarily.

Japan's chief cabinet secretary, Shinzo Abe, said Thursday that both countries are hoping for a peaceful resolution. Abe said a calm response is necessary, and that contacts between Japan and South Korea are taking place.

Japanese Foreign Minister Taro Aso says talks have been going on between vice ministers and ambassadors of both countries.

But South Korean President Roh Moo-hyun is continuing to talk tough. A day after he suggested Seoul's days of "quiet diplomacy" with Japan may be ending, he hinted Thursday at a further hardening of his foreign policy.

In a meeting with Christian leaders, Mr. Roh said good will alone may not be enough to resolve the dispute.

Mr. Roh said South Korea is facing a difficult situation, which may not be solvable with words alone. He said South Korea will need both wisdom and courage in the days ahead.